DESCRIPTION(provided by applicant): We are applying for funds to purchase a Zeiss LSM 510 laser scanning confocal microscope (LSCFM) equipped for simultaneous three-color analysis, 3D reconstruction, quantitative colocalization and time-lapse recording. The primary need for a new confocal microscope relates to imaging studies of host-pathogen interactions that require work with BL2 level pathogens. Typically, these interactions are highly dynamic, necessitating that living cells be imaged in real time during the interaction with live microbes. Examples include rearrangements of the cytoskeleton during entry, release of secretory proteins, alterations in cell signaling, and redistribution of host or microbial components. LSCFM is ideally suited for such studies due to the high spatial resolution, time-lapse acquisition, and 3D reconstruction features that will enable quantitative analyses of interactions between microbes and their host. The primary user group includes eight separate NIH-funded laboratories, affiliated with the Program in Microbiology and Microbial Pathogenesis at Washington University School of Medicine, working on a variety of microbial-host interactions that include parasitic, bacterial, viral and fungal pathogens. To facilitate operations, the LSCFM will be housed in a dedicated Imaging Facility with BL2 approved facilities, and overseen by an internal advisory committee. The Microbiology Imaging Facility will be staffed by a Ph.D. level scientist with experience in microbiology and microscopy, who will be responsible for training, operations, and assistance with experimental design and analysis. This instrument will greatly strengthen the research programs of these highly productive groups by applying high-resolution confocal microscopy to the study of human pathogens.